As telecommunication technologies evolve, the mobility of terminal devices has been enhanced greatly. Multi-hop networks have also been deployed more widely. In the multi-hop network, the mobility of terminal devices can be fairly ad hoc. The terminal devices can move freely within one network or between different networks. Additionally, the terminal devices can be turned on or off randomly. Due to these rapid changes that may happen randomly in the multi-hop network, as well as the changes caused by the torrential difference and the interference among wireless channels, the topology structure of the multi-hop network may change accordingly. Unfortunately, such structural change cannot be predicted. Thus, it is difficult for the conventional network routing protocols to reflect the changing topology in real time. Furthermore, the control signals sent in the network for maintaining the topology can cause excessive transmission overhead, wasting a great portion of the network bandwidth, and consequently degrading network performance.
In the multi-hop network, most conventional routing protocols adopt the Distributed Bellman Ford (DBF) algorithm or link state (LS) routing to route data within the network. Due to the distributed nature of the DBF, it is simple to deploy and can effectively compute the single-source shortest paths in the network. However, slow convergence and a tendency to create routing loops make the DBF not suitable for the type of network having rapid topology changes. Although some solutions have been utilized to resolve the routing loop problem, the slow convergence of the DBF remains a problem in the art.
Some adopt the link state routing protocol to solve the slow convergence problem of the DBF. In the link state protocol, every node in the network constructs a map of the connectivity of the network in the form of a graph showing which nodes are connected with other nodes; as a result, the looping problem can be easily avoided. Additionally, since any changes in the links will trigger real time updates, it takes less time to converge new topology than the DBF does. However, the link state protocol requires each switching node in the network to send its information about its neighbors to the entire network, and thus results in high overhead, especially in the network where frequent changes occur. Massive update messages occupy a great portion of the valuable bandwidth, degrading the network performance.
Therefore, what is needed is wireless communication a method for supporting rapid network topology changes with low overhead costs and devices of the same.